(a) Field of the Invention
The present invention relates to a fabrication method for a rear-projection screen and, more particularly, to a fabrication method capable of improving the manufacturing accuracy of the light-shielding layer in a rear-projection screen.
(b) Description of the Related Art
Referring to FIG. 1A, a conventional rear-projection screen includes a Fresnel lens 102 and a lenticular lens sheet 104. The light emitted from a projection lens is aligned as parallel light after passing through the Fresnel lens 102, and, after further refracting on the lenticular portions 104a of the lenticular lens sheet 104, the parallel light is focused on the planar surface of the lenticular lens sheet 104 opposite to the lenticular portions 104a to thereon form an image sensed by human eyes.
FIG. 1B shows a perspective view of a rear-projection screen 100, where black colored strips 108 functioning as a light-shielding layer are clearly illustrated.
When illuminating the lenticular portions 104a, the parallel light is concentrated as a plurality of bright stripes on the planar surface of the lenticular lens sheet 104. Hence, a light-shielding layer, such as the black colored strips 108, is need to cover all the planar surface of the lenticular lens sheet 104 except the regions on which the bright stripes are located, preventing stray light from striking the lenticular lens sheet 104 to improve image contrast.
FIGS. 2A to 2E show sectional plan views illustrating the conventional steps in forming a lenticular lens sheet 104 with a light-shielding layer.
First, as shown in FIG. 2A, a substrate 114 having lenticular portions 112 on one surface is prepared. Next, as shown in FIG. 2B, a light-curing resin layer 116 is applied on the planar surface of the substrate 114 opposite to the lenticular portions 112. Then, the planar surface of the substrate 114 is vertically irradiated from the lenticular portions 112 side with ultraviolet (UV) rays 118 extending in the longitudinal direction of the lenticular portions 112, as shown in FIG. 2C. Hence, parts of the resin layer 116 are cured corresponding to the locations at which light is focused by the lenticular portions 112 acting as a cylindrical lens. Cured layers 116a and uncured layers 116b are both formed in the resin layer 116.
Subsequently, referring to FIG. 2D, a transfer sheet 122 having a black colored layer 120 is overlaid on the entire planar surface of the substrate 114, and the black colored layer 120 is caused to stick to only the uncured layers 116b due to their adhesion. Finally, as shown in FIG. 2E, the transfer sheet 122 is peeled from the substrate 114 to remove parts of the black colored layer 120 correspond to the cured layers 116a. With this process, a light-shielding layer consisting of black colored strips 124 is formed corresponds to the uncured layers 116b. 
However, this method is liable to result in an alignment error in the formation of the black colored strips 124, particularly under the fabrication of a large-sized screen. Also, when the black colored layer 120 is peeled from the transfer sheet 122, the resulting shear force may cause the black colored strips 124 to have an uneven edge to lower their shielding effect. Once there is a need for enhancing image resolution by diminishing the interval between two adjacent projections of the lenticular portions 112, the defects mentioned above will become more apparent.
Further, a large-scale rolling machine is needed to combine all optical layers, such as the light-curing resin layer 116 and the black colored layer 120, thus resulting in a high manufacturing cost.